When does an immigrant become British

The 'liberal' consensus as spread by the BBC tells us that as soon as someone starts to live in the Britain they become, in some way,  British and worthy of the support of this country. Men such as Binyam Mohamed, are called British residents, when they are not British in any normal sense of the word, and their protection by Britain is called for. However the 'liberal left' also love to point out that the the British Queen is German despite her being born in the UK as with her father and his father before him. I was reminded of this by an excellent post by commenter 'It's all too much' at Biased-BBC, here's the meat of his post (with the spelling corrected, as requested):

'I never got round to making the comment on the 'horrible histories' thread (way down below) - the children's programme proving that there were no 'British things' and that 'British culture was a stolen mish mash from older, wiser, more humane cultures.   


It struck me as odd that Queen Victoria was held up to contempt because she "wasn't British" - she was a "German".  Now she was born in Kensington Palace; her father was born in Buckingham palace; her Grand father George III was born in London in Norfolk house, it was only her great Grandfather George II who was born in Hanover (not Germany because it didn't exist.)

So Victoria was a third generation 'migrant' but she wasn't British!  Correct me if I am wrong but isn't it "racist"in 21st century Britain (wherever that is) to question the 'Britishness' of immigrants - even if they have just arrived 'informally' in a veg truck from the Balkans or are fresh from the Souk at Mogadishu?  Isn't Bib Bag Mohhamed a heroic 'British resident' even though he has an Ethiopian passport.

Is the BBC arguing that there is some sort of indigenous cultural identity that foreigners cannot assimilate even after 3 or 4 generations?  Is it criticising Queen Victoria for maintaining close cultural ties with her 'parent culture', speaking her 'first language' at home occasionally and importing a spouse from her 'homeland'?  

I am fairly certain that if I posed a complaint - that the programme denigrated immigrants and the concept of multiculturalism - pants would be soiled in the producers 'strategy brain storming' session.....'

Being a 'liberal' must be so freeing for the brain...